Phone Phreaking
Before computer hackers, there were phone phreaks—people who exploited the telephone system for free calls and exploration. Using devices like the 'blue box,' they manipulated telephone company signaling to make calls anywhere in the world.
The Culture of Exploration
Phone phreaking began with technical curiosity. The telephone network was the largest and most complex machine on Earth, and some people couldn't resist exploring it. They developed subcultures, newsletters (like the legendary 2600), and meetups at conventions.
The Blue Box
AT&T's长途电话网络 used in-band signaling—control tones traveled on the same 线路 as voice calls. This meant anyone with the right tone generator could manipulate the network. The "blue box" generated these tones, including the sacred 2600 Hz signal that indicated an open line.
Cap'n Crunch and John Draper
The most famous discovery: a toy whistle from Cap'n Crunch cereal produced a perfect 2600 Hz tone. John Draper (aka "Captain Crunch") used this whistle to make free calls. He taught others, including future Apple founders Steve Jobs and Steve Wozniak, who built their own blue boxes.
Steve Jobs and the Blue Box
In a 1994 interview, Steve Jobs revealed that Wozniak built a blue box for him in 1972. Jobs said: "We never paid for a call in our lives... We made about $6,000 in quarters with that box. It was a lot of money in those days."
The End of In-Band Signaling
AT&T eventually switched to out-of-band signaling (SS7), separating control from voice. This made traditional phreaking obsolete. By the 1980s, computer hacking had replaced phone phreaking as the primary form of unauthorized system access.